Chalcedony. Chalcedony occurs only in Revelation 21:19. The name is applied, in modern mineralogy, to one of the varieties of agate. It is generally translucent and exhibits a great variety of colors. So named because, it was found near the ancient Chalcedon, near Constantinople.
More than 4,500 subjects and proper names are defined and analyzed with corresponding Scripture references. Bible students have used "Smith's Bible Dictionary" since its introduction in the 1880s, making it a trustworthy classic.Wikipedia
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